Mineral oil, a traditional equine laxative, clears sand from the equine intestine more effectively when used in conjunction with psyllium, according to new research from the University of Veterinary Medicine Vienna, in Austria. These results are especially important for horse owners in geographical areas where the incidence of sand colic is high.

In this study, researchers quantified the amount of crude ash excreted by horses that were fed identical quantities of sand. In this crossover study, the researchers examined 12 horses' sand output after administering mineral oil alone and mineral oil in conjunction with psyllium, a bulk-forming laxative made from the seeds of Plantago plants. Each group was examined under both treatment protocols, with a rest period between study phases.

The horses were given sand for five days. Following the "loading" period, they were treated according to their assigned group. Total feces were collected and weighed daily during the treatment period and were examined for crude ash output, which is indicative of the amount of sand passed.

While some horses naturally cleared sand more effectively than others, the researchers found the mineral oil/psyllium combination to be more effective overall than oil alone. Horses treated with psyllium and oil together excreted a mean of 51% of the sand administered, compared to 26.1% when administered oil alone. The study authors noted that the effectiveness of psyllium given alone should be examined in a future study using these protocols, as psyllium is easy to administer as a top dressing on feed and clearly indicated for use as a prophylactic treatment for horses living in sandy areas.

According to Christine Iben, VMU, DVPH, faculty member in the Department of Veterinary Public Health, a part of the Institute of Nutrition at the University of Veterinary Medicine Vienna, and lead author on this study, future research projects will be designed to further the scientists' understanding of the role of mineral oil. The researchers will also work to calculate the lowest effective dose of psyllium.

"As soon as we will get some financial support for further trials, we will continue," Iben said.

The study, "Evacuation of sand from the equine intestine with mineral oil, with and without psyllium," was published in the February 2008 Journal of Animal Physiology and Animal Nutrition.